Two stage hydrocarbon conversion process with hydrocracking of the residual oil fromthe second stage, in the first stage



3,180,817 TWO STAGE HYDROCARBON CONVERSION PROCESS WITH HYDROGRACKINGApril 27, 1965 w. H. CLAUSSEN ETAL OF THE RESIDUAL OIL FROM THE SECONDSTAGE,

THE FIRST STAGE Filed Dec. 3, 1962 3 MN :.omm \w w. 3 2 W ud w- W. A r mS N w 85 3755 A m omm com .2 a Q \h a d v wzoN w 0223 522: u 2 o k N 2 h.oom ..o2 a 2 w 2 a N: hrofi o 2 w. m N o ATTORNEYS fi aip mZON UnitedStates Patent M INTRODUCTION This invention relates to a hydrocarbonconversion process, more particularly to a hydrocarbon conversionprocess for converting petroleum distillates and residual into variousvaluable products, and still more particularly to a catalytic conversionprocess capable of producing middle distillates, heavy gasoline andlight gasoline.

PRIOR ART HYDROCRACKING OF HYDRO-CAR- BON FEEDS TO PRODUCE MIDDLEDISTIL- LATES AND GASOLINE, AND PROBLEMS IN- VOLVED A. Nitrogen content0 feed-It is Well known that nitrogen in a hydrocarbon feed isdeleterious to certain hydrocracking catalysts, particularly highlyacidic hydrocracking catalysts, and that, in order to provide a practical process for producing gasoline from a feed containing substantialamounts of nitrogen, a first stage catalyst relatively insensitive tonitrogen poisoning and having no more than Weak acidity has beennecessary. However, such catalysts having no more than weak acidityfrequently result in the production of substantial quantities of middledistillates, heavy gasoline and even heavier materials, although they doproduce some light gasoline.

B. Ratio of lira-C to normal-C product.It is well known that a highiso-C, to normal-C product from a hydrocracking zone is highlydesirable. Isobutane, for example, is a valuable product for use inmotor gasoline blending, whereas normal butane is less valuable. A lowiso-C, to normal-C product ratio has been a disadvantage of many priorart processes.

C. Parafiinicity of unconverted bottoms fraction recycled to react0r.ltis well known that various prior art catalysts, particularly catalystsof extremely low activity which are useful in the production of middledistillates and catalysts of extremely high activity which are useful inthe production of gasoline, produce an unconverted bottoms fractionhaving a high content of normal paraffins. It is known that these normalparafiins are deleterious to the hydrocracking operation because theyare extremely refractory to further hydrocracking and therefore,particularly where high middle distillate production is desired, as apractical matter, cannot be recycled. It would be desirable if atwo-stage process were available for producing middle distillates, lightgasoline and heavy gasoline in both stages without producing a firststage bottoms product having a normal paraffin content too high topermit a practical recycle thereof to the first stage.

D. Regenerati0n.-It is known that many prior art hydrocracking catalystslose a great deal of their fresh catalyst activity upon regeneration,and it would be very desirable if the catalysts used in processes formeeting the foregoing prior art problems were regenerable.

OBJECTS In view of the foregoing, it is an object of the invention toprovide a two-stage process using selected catalysts, capable ofconverting both hydrocarbon feed stocks that 3,180,817 Patented Apr. 27,1965 have a high nitrogen content and those that have been denitrified,to produce middle distillates, heavy gasoline and light gasoline in'large quantities, while minimizing light gas production, at reasonablestarting and operating temperatures.

' It is a further object of the present invention to provide such aprocess and catalysts wherein the unconverted bottoms fraction from thefirst stage has a sufficiently low content of normal parafiins to permitrecycling a selected portion of this fraction to the first stage reactorin sustained recycle operation, to increase the overall yield ofgasoline.

It is a further object of the present invention to provide such aprocess wherein the catalysts in each stage may be regenerated toreimpart to them a substantial portion of their original fresh activity.

DRAWING The invention Will best be understood, and further objects andadvantages thereof will be apparent, from the following description whenread in conjunction with the accompanying drawing which is adiagrammatic illustration of process units and flow paths suitable forcarrying out the process of the invention.

STATEMENT OF INVENTION In accordance with the present invention, thereis provided a process for producing gasoline and middle distillates froma hydrocarbon feed selected from the group consisting of petroleumdistillates boiling from 650 to 1100 F. and petroleum residua boilingabove 650 F., which comprises contacting said feed and from 1000 to10,000 s.c.f. of hydrogen per barrel of said feed in a first conversionzone at a temperature of from 500 to 950 F., a pressure above 500p.s.i.g. and an LHSV of 0.1 to 4.0 with a catalyst comprising at leastone hydrogenating component selected from the Group VI metals andcompounds of Group VI metals and at least one hydrogenating componentselected from the Group VIII metals and compounds of Group VIII metalson a catalyst support comprising silica-magnesia, recovering from theefliuent from said first conversion zone a middle distillate product, aheavy gasoline product and a light gasoline product, hydrocracking in asecond conversion zone in the presence of an active acidic hydrocrackingcatalyst a portion of the eifiuent from said first conversion zoneboiling above about 650 F., and recovering from said second conversionzone a middle distillate product, a heavy gasoline product and a lightgasoline product.

Further in accordance with the present'inventiomthere is provided aprocess 'for producing gasoline and middle distillates which comprisesconverting a heavy gas oil feed boiling above about 650 F. in a firstconversion zone in the presence of a catalyst comprising nickel andtungsten on a silica-magnesia support at a temperature of from 500 to:950 F., a pressure above 500 psig. and

an LHSV of from 0.4 to 2.0, to a total product contain- 7 ing above 60volume percent, based on feed converted, of 320 to 650 F. middledistillate, separating said total product into fractions including amiddle distillate fraction and a gasoline fraction, recovering saidmiddle distillate and gasoline fractions as products, hydrocracking in asecond conversion zone in the presence of an active acidic hydrocrackingcatalyst a portioh 'of the effluent from said first conversion zoneboiling above about 650 F., recovering a gasoline product from saidsecond conversion zone, and recycling to said first conversion zone atleast a portion of the effluent from said first conversion zone boilingabove about 650 F.

Still further in accordance with the present invention, there isprovided a process for converting a nitrogen containing hydrocarbon feedselected from the group consisting of petroleum distillates boiling from650 F. to 1100 F. and petroleum residua boiling above 650 P. whichcomprises concurrently hydrofining and hydrocracking said feed bycontacting said feed in a first stage in the presence of from 1000 to10,000 s.c.f. of hydrogen per barrel of said feed and in the presence ofa catalyst comprising at least one hydrogenating component selected fromthe group consisting of Group VI metals and compounds thereof and atleast one hydrogenating component selected from the group consisting ofGroup VIII metals and compounds thereof on a silica-magnesia catalystsupport at a temperature of 500 to 950 F., a pressure above 500 p.s.i.g.and an LHSV of from 0.1 to 4.0, hydrocracking in a second stage in thepresence of an active acidic hydrocracking catalyst at least asubstantial portion of the liquid efiluent from said first stage boilingabove about 650 F., recovering a gasoline product from said secondstage, and recycling to said first stage at least a portion of theefiluent from said first stage boiling above about 650 F., and recyclingto said first stage at least a portion of the effiuent from said secondstage boiling above about 650 F.

Still further in accordance with the present invention, there isprovided a process as aforesaid wherein at least two reactors are usedin said first conversion zone, each containing said silica-magnesiasupported catalyst, and wherein said reactors are so arranged that theycan be switched from parallel, for maximizing middle distillateproduction, to series, for maximizing either gasoline or middledistillate production, whereby the ratio of middle distillate product togasoline product can be varied.

HYDROCARBON FEEDS SUITABLE FOR USE IN THE PROCESS OF THE PRESENTINVENTION Suitable feeds for use in the process of the present inventionare petroleum distillates boiling from 650 to 1100 F., and petroleumresidua boiling above 650 F., and mixtures of the foregoing. Heavy gasoils and catalytic cycle oils are excellent feeds to the process as wellas conventional FCC feeds and portions thereof. Residual feeds mayinclude Minas and other parafiinic-type residua.

The present process is particularly capable of producing middledistillates, including jet fuels, which are exceptionally high innaphthene content and low in aro matic content (therefore having highsmoke points) and low in normal paraffin content (therefore having lowfreeze points). The feed to the present process, with an initial boilingpoint above 650 F., is converted directly to a synthetic material, i.e.,one boiling below the initial boiling point of the feed, which is apreferred jet fuel or middle distillate having high naphthene content,low normal paraffin content and therefore low freeze point, and lowaromatic content and therefore exceptionally high smoke point. It hasbeen found that feeds having lower initial boiling points, for examplearound 300 to 400 F., tend to produce excessive quantities ofnonsynthetic products having high aromatics content and thereforeexceptionally low smoke points, although the freeze point may besatisfactory. Such a nonsynthetic product also tends to have a high pourpoint.

FIRST CONVERSION ZONE IN PROCESS OF PRES- ENT INVENTION, AND NITROGENCONTENT OF FEED THERETO It has been found that the silica-magnesiasupported hydrocracking catalyst in the first conversion zone of theprocess of the present invention is relatively nitrogen insensitive,compared with conventional acidic hydrocracking catalysts such as nickelsulfide on silica-alumina. Accordingly, the nitrogen content of the feedused in the process of the present invention may be relatively high, andexcellent hydrocracking results still may be obtained in said conversionzone at reasonable temperatures, without the necessity for rapidlyraising the temperature to maintain conversion as is necessary whenhydrocracking a high nitrogen content feed over a conventional acidichydrocracking catalyst such as nickel sulfide on silicaalumina. Althoughhigh nitrogen content feeds can be tolerated by said first conversionzone hydrocracking catalyst, it will be noted that said catalyst also isan excellent hydrodenitrification catalyst, and is efficient inconcurrently hydrofining as well as in hydrocracking the feed.Nevertheless, the process of the present invention may be rendered evenmore efiicient if the feed either is low in nitrogen content or first ishydrofined by conventional methods prior to being hydrocracked in saidfirst conversion zone in accordance with the process of the presentinvention. And in certain applications a conventional hydrofining zonefollowing said first conversion zone is desirable; as will be discussedbelow, in one embodiment of the present invention, wherein very heavyfeeds, for example propane deasphalted residua, are used, the feed maybe processed in three stages; in the first stage, the feed may beconcurrently hydrocracked and denitrified to a large extent over asilica-magnesia supported catalyst, following which a portion of theeflluent from the first stage may be further denitrified in a secondstage before being hydrocracked over an acidic hydrocracking catalyst ina third stage.

Generally speaking, it is possible to operate the first conversion zonein the process of the present invention at slightly lower temperatureswhen the feed has a low nitrogen content, for example from 0 to 10 ppm.total nitrogen, than temperatures that are necessary for the sameconversion when the feed hasa high nitrogen content, for example from 10to 1000 ppm. total nitrogen. However, even feeds containing considerablyhigher levels of nitrogen than 1000 ppm. total nitrogen may besatisfactorily converted in the process of the present invention tovaluable products, contrary to conventional prior art processes whereinacidic hydrocracking catalysts, such as nickel sulfide onsilica-alumina, are used. In such conventional processes, it isimpossible as a practical matter to use feeds with such high nitrogencontents.

The catalyst in the first conversion zone in the process of the presentinvention is capable of concurrently accomplishing both denitrificationand hydrocracking. The hydrocracking facilitates the concurrentdenitrification because, upon the breaking of carbon-to-carbon bonds,nitrogen is more easily removed. At higher levels of crackingconversion, somewhat higher pressures may be desired to counteractcatalyst fouling and deactivation.

The nitrogen compounds tend to concentrate in the heavier portions ofthe feed; accordingly, such heavier portions are more difiicult todenitrify. However, it will be noted from the foregoing that suchheavier portions also are easier to crack.

OPERATING CONDITIONS IN FIRST CONVERSION ZONE The first conversion zoneof the process of the present invention, which contains asilica-magnesia supported catalyst, discussed below, is operated atcombinations of conditions selected from Within the varying ranges thatwill produce the desired degree of hydrocracking: a temperature of about500 to 950 F., preferably 650 to 850 F.; a hydrogen partial pressure of500 to 3500 p.s.i.g., preferably 1000 to 2500 p.s.i.g.; and an LHSV offrom about 0.1 to 4.0, preferably 0.4 to 2.0. The hydrogen flow to saidconversion zone is from 1000 to 10,000 s.c.f. per barrel of feed, andpreferably 2500 to 8000 s.c.f. per barrel of feed. The higher hydrogenpartial pressures, particularly with unrefined feeds, give lowercatalyst fouling rates and therefore for longer catalyst lives it ispreferable to operate above 2000 p.s.i.g. In general, the hydrogenpartial pressure will depend upon a number of factors, including type offeed stock and nitrogen content thereof, degree of denitrification re-CATALYST IN FIRST CONVERSION GROUP A. Composition of catalyst-It isessential that the catalyst in the first conversion zone in the processof the present invention have (a) a silica-magnesia support, and (b) atleast two hydrogenating components, at least one of which must be aGroup VI metal or compound thereof and at least one of which must be aGroup VIII metal or compound thereof. It has been found that, where thecatalyst comprises a Group VI metal or compound thereof alone, without aGroup VIII metal or compound thereof, the catalyst has an unacceptablylow activity. It has been found that, Where the catalyst comprises aGroup VIII metal or compound thereof alone, without a Group VI metal orcompound thereof, the catalyst has an exceptionally high fouling rate.However, where the catalyst comprises at least one Group VIII metal orcompound thereof and also at least one Group VI metal or compoundthereof, the catalyst has a high activity and a low fouling rate. TheGroup VI metals and compounds thereof that may be used include chromium,molybdenum and tungsten and compounds thereof. The Group VIII metals andcompounds thereof that may be used include iron, cobalt, nickel,platinum, and palladium and compounds thereof. The most preferredcatalysts comprise nickel and either tungsten or molybdenum on asilica-magnesia support, the catalyst in each case preferably beingsulfided. The single main preferred catalyst which has been found tohave the most outstanding qualities in the process of the presentinvention comprises nickel and tungsten on silica-magnesia, preferablysulfided. The Group VI metal or compounds thereof may be present in thecatalyst in an amount from 1 to 40 weight percent, preferably from 2 to25 weight percent, based on the total catalyst composite; the Group VIIImetal or compound thereof may be present in an amount of from 1 to 20weight percent, preferably from 2 to 12 weight percent, based on thetotal catalyst composite. The magnesia content of the silicamagnesiasupport may range from 5 to 75 weight percent, preferably from to 50weight percent, and still more preferably from to 35 weight percent.

B. Preparation of catalyst-The silica-magnesia support of the catalystcan be prepared by any conventional method, and the plurality ofhydrogenating components may be incorporated in the catalyst by anyconventional method. A particularly effective method for preparing thecatalyst is set forth in the following example.

Example I A powdery silica-magnesia material containing about 20%magnesia was compressed, together with about 5% by weight of aconventional glue-type bonding material used in catalyst preparation,into x pellets, and was calcined in air at 950 F. for six hours.

1000 cc. of the aforesaid calcined material were impregnated for fourhours with 800 cc. of a solution of nickel nitrate containing 11.2%nickel, and the impregnated material was dried for 24 hours at 250 F.and then calcined for four hours at 900 F. The resulting product was acatalyst supportcontaining 9.43% nickeL' The aforesaid catalyst supportwas impregnated three 7 times with separate 800 ccJportions of asolution consisting of 960g. of tungstic acid (H WO dissolved in amixture of.1152 cc. of ammonia (NH and 3460 cc. of

water. ments, the impregnated composite was dried at 250 F.

substantial amounts of sulfur compounds, the catalyst automatically willtend to become sulfided on the surface under the operating conditions ofthe process. It is somewhat rnore preferable to presulfide the catalystbefore placing it on-stream, and such sulfiding may be accom plished byany conventional method.

D. Regeneration of the catalyst.lt is an outstanding advantage of thecatalyst of the present invention that it may be regenerated,particularly in view of the difficulties that have been met. by the artin the regeneration of many prior art catalysts. While regeneration maybe accomplished by any conventional method, and while the relativeeffectiveness of such methods may be readily determined by those skilledin the art, the regeneration method set forth in Table IV below is ahighly effective one.

B. Preferred catalysts.-The preferred catalysts for use in the processof the present invention are set forth above.

F. Activity 0 catalyst for denitrificati0n.The catalyst of the presentinvention is a denitrification catalyst, as well as a hydrocrackingcatalyst, and in the process of the present invention performs bothfunctions under the conditions of the process. The catalyst hasexcellent denitrification activity, but it is relatively insensitive tonitrogen,

, and is highly insensitive to nitrogen compared with a con- After eachof the aforesaid impregnation treat- 7 for 20 hours, and calcined at 900F. for four hours. The

C. Sulfiding the catalyst.Although the catalyst of the present inventionmaybe used in the unsulfided form, the sulfided form is preferable. Withfeeds containing any 'of the two groups.

ventional acidic hydrocracking catalyst such as nickel sul-' fide onsilica-alumina.

Not only are a plurality of hydrogenation components, at least one ofwhich must be a Group VI metal or compound thereof and at least one ofwhich must be a Group VIII metal or compound thereof, essential to thehydrocracking activity of the catalyst of the present invention, butthis same plurality of hydrogenation components is essential to thedenitrification activity of the catalyst of the present invention. Forexample, the preferred nickeltungsten on silica-magnesia catalyst of thepresent invention would not have good denitrification activity if onlynickel or only tungsten were present; single hydrogenating components,for example molybdenum or tungsten from Group VI or nickel or cobaltfrom Group VIII, are relatively ineffective for denitrification when notaccompanied by a hydrogenating component from the other one- Furtherinformation regarding the denitrification activity of the catalyst isset forth in Table V below. a

G. Selectivity of catalyst for middle distillate producti0n.--Thecatalyst of the present invention has a high selectivity for theproduction of middle distillates from various hydrocarbon feeds. It hasa much greater selectivity for the production of middle distillates thanconvenventional acidic hydrocracking catalysts, such as nickel sulfideon silica-alumina. The high yields of middle distillates resulting fromthe selectivity of the catalyst of the present invention for middledistillate product is unexpected in view of the selectivity for gasolineproduction that is characteristic of many prior art hydrocrackingcatalysts, for example nickel sulfide on silica-alumina. Furtherinformation regarding the selectivity of the present invention catalystfor the production of middle distillates is set forth in Table IIIbelow.

DESCRIPTION OF PROCESS FLOW ARRANGE- MENTS SUITABLE FOR. CARRYING OUTTHE PROCESS OF THE PRESENT INVENTION Referring now to the drawing, thereshown is a diagrammatic illustration of an embodiment of process unitsand flow pathssuitable for carrying out the process of the presentinvention.

[zone 5 from which hydrogen is recycled through line 6,

ammonia is withdrawn through line '7, and remaining materials are passedthrough line 8 to separation zone 9.

(1 From separation zone 9 a C and lighter stream, including isobutane,is withdrawn through line 10, and remaining materials are passed throughline to separation zone 16. From separation zone 16 a light gasolineproduct is Withdrawn through line 17, a heavy gasoline product boilingfrom about 180 to 300 F. is withdrawn through line 18, and materialsheavier than about 300 F. are passed through line 20 to separation zone25.

From separation zone middle distillate products boiling from about 300to 650 F. are withdrawn through line 26 and materials boiling aboveabout 650 F. are recycled through line 27 to hydrocracking zone 2. Ifdesired, a minor portion of the materials in line 27 may be withdrawnfrom the system through line 28. A portion of the materials in line 27are passed through line 37 to hydrocracking zone 19, the exact amountdepending upon the desired ratio between the products from hydrocrackingzone 2 and the generally lighter products from zone 19. Hydrocrackingzone 19 may contain a conventional acidic hydrocracking catalyst, forexample nickel sulfide on silica-alumina, platinum on silica-alumina,etc., and may operate under conventional hydrocracking conditions, forexample a pressure of from 500 to 3000 p.s.i.g. and a temperature offrom 550 to 850 F. It is well known that such catalysts can be subjectedto regeneration with an oxygen-containing gas under conventionalregeneration conditions. Hydrocracking zone 19 is supplied with hydrogenthrough line 35. Zone 19 efiluent may be passed through line 36 toseparation zone 16.

Hydrocracking zone 2 may comprise two hydrocracking reactors, eachcontaining the catalyst of the present invention and each operatingunder the aforesaid process conditions. These two reactors may bearranged in a known manner so that alternately they can be connected inparallel and in series. When connected in parallel, they will operate tomaximize middle distillate production, and when switched to seriesoperation they may maximize gasoline or middle distillate production. Inseries operation, middle distillate production may be maximized bywithdrawing middle distillate. as a product from the first reactor aswell as from the second, for example from an interreactor fractionationzone. In series operation, gasoline production may be maximized byincluding the middle distillate produced in the first reactor in thefeed to the second reactor. In either series arrangement, it ispreferred to remove from the system any ammonia produced in the firstreactor, rather than permitting it to pass to the second reactor. Suchswitch.- ing arrangements will enable the ratio of middle distillate togasoline product to be varied in order to achieve further processapplication flexibility. In series operation to produce gasoline, whereammonia formed in the first reactor has been removed, the secondreactor,because it is operating with a feed that has been denitrified in thefirst reactor, is operable at lower temperatures, thus providing leewayfor increase in severity of the operating conditions in the secondreactor to increase gasoline production. The resulting gasoline,produced over the catalyst of the present invention, is isoparaffinicand of high quality, in contrast to the normal parafi'inic character ofgasoline produced over hydrocracking catalysts having weak acidity.

Because the catalyst in zone 2 serves as an effective hydrofiningcatalyst, the materials in line 8 are low in nitrogen and therefore areespecially suitable for further hydrocracking in the presence of theacidic catalyst in zone 19.

The process of the present invention is especially effective forconverting heavy feed such as residua and propane deasphalted oils whena conventional denitrification zone is inserted between the firsthydrocracking zone and the second hydrocracking zone of the process.Because such feeds generally are especially difiicult to denitrify, andbecause for most efiicient results the feed to the second conversionzone 19 here, containing an acidic hydrocracking catalyst, should have aminimum nitrogen level, the insertion of a conventional denitrificationzone between the two hydrocracking zones in the present process can beof significant value.

The conventional denitrification zone may be inserted, for example, inline 8 or line 15, and may be operated under conventionaldenitrification conditions With either the silica-magnesia supportedcatalyst used in hydrocracking zone 2, or with any conventionaldenitrification catalyst. Such a three-stage process enables the heavierfeeds to be hydrocracked and partially denitrified in the first stage,thereby reducing both the molecular weight and the nitrogen level of thefeed and greatly accelerating the rate of the remaining denitrificationto be accomplished in the second, or conventional, denitrification zone.

TABLE I.COMPARISON OF FIRST STAGE CATALYST OF PROCESS OF PRESENTINVENTION WITH CON- VENTIONAL CATALYSTS RE STARTING TEMPERA- TURES ANDFOULING RATES The following table sets forth on a comparative basissingle stage hydrocracking results of processing a 650 to 980 F. heavyArabian gas oil having a total nitrogen content of 660 to 700 ppm. atthe indicated average catalyst temperature, about to volume percentsubstantially constant per-pass conversion to products boiling below theinitial boiling point of the feed, 1.0 LHSV, 2000 p.s.i.g. and ahydrogen rate sufilcient to permit withdrawal from the hydrocrackingzone of 4500 s.c.f. of hydrogen per barrel of feed, over the first stagecatalyst of the present invention compared with hydrocracking the samefeed under the same conditions over various prior art catalysts. Thefactors compared are: 1) the average catalyst temperature necessary togive said substantially constant 50 to 55% per-pass conversion, whichsubstantially constant conversion is indicated by the substantiallyconstant product gravity shown; and (2) the catalyst fouling rate.

Support Hydrogenating com- Av. eat. Cat. ponent (percent) Area, tomp.,F. Product Fouling N 0. mJ/g. necessary gravity rate for desiredSlOz-AlgOa, SiOz-MgO Ni W Mo Pt conversion 1 27% MgO 759 40. 0 Noneobservable. 2 27% MgO" 755 40. 3 D0. 3. 27% Mg0 756 39. 9 Moderate. 4-27% Mg0 767 39. 5 Do. 5--- 27% MgO 790 39. 5 High. 6 27% Mg0 765 40. 3Very high. 7 27% MgO 845 38. 5 Do. 8... 25% A1203. 790 40. 3 Noneobservable. 9.-. 28% A1203. 792 40.0 Moderate. 10. 47% A1203. 780 40. 0D0. ll 47% A1203- 790 39. 8 D0. 12 10% A1203- 805 39. 8 High.

B 0.05 F. per hour.

b -0.100.15 F. per hour.

6 -0.5 F. per hour. 4 -1.0 F. per hour.

lysts 1 to 4 resulted in both (1) the desired conversion rate atareasonably low average catalyst temperature, in each case 767 F. orbelow, and (2) a reasonably low catalyst fouling rate, in each case,moderate, as defined, or less. It will be noted that catalysts 5 to 7,each having one hydrogenating component only, on a silicamagnesiasupport, resulted in an excessive catalyst fouling rate, i.e., one thatwas high, as defined, or higher. It will be noted that catalysts 8 to12, each having a silica alumina support rather than the silica-magnesiasupport of the first stage catalyst of the present invention, resultedin the desired conversion being obtained only at an unreasonably highaverage catalyst temperature, in each case 780 F. or above.

TABLE II.'COMPARISON OF FIRST STAGE CATALYST OF PRESENT INVENTION WITHCONVENTIONAL CATALYSTS RE ACIDITY, STARTING TEMPERATURE, ISO TO NORMALCi PRODUCT RATIO, MIDDLE DIs- TILLATE T GASOLINE PRODUCT RATIO AND NOR-lgoAfisPARAFFlN CONTENT OF UNCONVERTED BOT- The following table setsforth on a comparative basis single-stage hydrocracking results ofprocessing an Arabian straight run feed, at 0.5 LHSV, 2000 p.s.i.a, 60%per-pass conversion to products boiling below the initial boiling pointof the feed, and extinction recycle, over the first stage catalyst ofthe present invention, compared with hydrocracking the same feed underthe same conditions over various prior art catalysts. The factorscompared are: (1) starting temperature necessary to give said 60%per-pass conversion; (2) the ratio of iC to nCi, in the product; (3) theratio of 400 to 650 F. product to C to 400 F. product; i.e., the ratioof middle distillate production to gasoline production; (4) the hydrogenconsumption, in s.c.f. per barrel of feed; and (5) the change, in F., ofthe pour point of the same bottoms fraction in each case, from the pourpoint of the feed, as an indication of the effect of the reaction ineach case on normal parafiins in the system.

dicated to have a greater normal parafiin content than the feed. WithCatalysts B, C and D the unconverted bottoms material is less paraffinicthan the feed, which is extremely desirable because normal paraifins arerefractory to hydrocracking and therefore build up in recycle bottomsduring recycle operation. A build-up of refractory normal paraffins caneffectively prevent the practical use of recycle hydrocracking toproduce middle distillates, because prohibitive temperature and pressureincreases can be required to crack these refractory compounds; (5) withCatalysts B, C and D the undesirable refractory normal paraffins areselectively cracked and/or are isomerized to valuable isoparaflins, toan extent adequate to permit satisfactory recycle operation.

TABLE III.-COMPARISON OF FIRST STAGE CATALYST OF PRESENT INVENTION WITHCATALYST HAVING SILICA-ALUMINA SUPPORT RE PRODUCTION OF MIDDLEDISTILLATES Total couver- Percent of Catalyst Temp, sion to prodproductin F. ucts boiling 400650 F.

below 650 F. boiling range NlW on SiOs-AlzOa 650 53. 2 41 NiW on SiO-MgO 650 53. 4 49 r TABLE IV.-REGENERAB1LITY on FIRST STAGE CAT:

ALYST OF PRESENT INVENTION AND REGENERATED CATALYST ACTIVITY I Start.400650 F./ H2, Bottoms Cat. Cat. comp. 'I., F iC /IIC 05-400" F.s.o.f./bbl. pour point change, F.

A 6% Ni+22% Mo on A1 03.-." 850 0. 2 1. 4 1,300 +13 B NiMo on Sim-A1 030% Sio 705 0.6 1. 4 1, 700 3s 0..... NiW on SiOz-MgO, 27% MgO- 7201.1 1. 4 2, 000 -25 D- NiMo on Sim-A1 03, 90% SiO2 790 0.6 0.9 1,800 156% Ni on Slog-A1203, 90% S102 740 1.1 0. 4 2,600 +19 The catalysts inthe above table are set forth in order of the present invention. Acatalyst comprising 7.0%

of increasing acidities, with Catalyst A having the lowest acidityincreases, the product iso to normal ratio inlyst C is an example of thefirst stage catalyst of the present invention, while the other catalystsindicated are representative of various prior art catalysts.- 7

From the above table it will be noted that: (1) as acidity increases,the prdouct iso to normal ratio increases smoothly, except in the caseof the first stage catalyst of the present invention, with which isobtained a higher ratio than would be expected'from inspection of theprior art catalysts alone; (2) as acidity increases, the product middledistillate to gasoline ratio decreases, but remains as high with thefirst stage catalyst of the present invention as with catalysts ofweaker acidity, which is entirely unexpected; heretofore, it has beenbelieved that a catalyst of higher acidity would produce less middledistillate per unit of gasoline production than a'more weakly acidiccatalyst; (3) as acidity increases, hydrogen consumption increasessmoothly, except in the case of the first stage catalyst of the presentinvention, with which is obtained a higher hydrogen consumption andimproved product quality; (4) as acidity increases, the normal parafiincontent of the uncoverted bottoms material, as indicated by the F.change in bottoms pour point from the pour point of the feed, decreasesand then increases; with Catalysts A and E the bottoms material isinnickel and 19.3% tungsten on a silica-magnesia support containing27.7% magnesia, with van area of 316 mF/gz, was placed in hydrocrackingreactor and contacted for 120 hours at 2000 p.s.i.g., 1.0 LHSV,759 F.average catalyst temperature, and hydrogen rate of 5500 s.c.f.

per barrel of feed, with a hydrocarbon feed boiling from 650 to 982 F.,said feed having agravity of 235 API, an aniline point of 178.9% F., apour point of ASTM and a total nitrogen content of 665 p.p.m. Thecatalyst under these conditions converted54 weight percent of the feedto products boiling below the 650 F. initial boiling point of the feed,and the gravity of the total products produced was 40.3 API.

After the foregoing on-stream period the catalyst was regenerated in anitrogen-oxygen stream, at a reactor pressure of 600 p.s.i.g. and a gasrate of 20 cubic feet per hour, for a total period of 20 hours. Duringthis period the temperature was slowly raised from 500 to 900 F., andthe oxygen content of the gas was raised from 0.1 to 4.0 volume percent.

The regenerated catalyst, having an area of 237 m. /g., was then used tohydrocrack the same feed that it had been used to hydrocrack prior toregeneration, under the same conditions. The activity of the regeneratedcatalyst was substantially equal to its original fresh activity, asindicated by its conversion, at an average catalyst tem- 1 1 perature of750 F., of 48 weight percent of the feed to products boiling below theinitial boiling point of the feed, the total products produced having agravity of 38.8 API.

The following summarizes the foregoing results:

TABLE V.--COHPARISON OF FIRST STAGE CATALYST OF PRESENT INVENTION WITHCONVENTIONAL CATALYSTS RE DENITRIFICATION ABILITY, NITRO- GENSENSITIVITY AND ABILITY TO CONVERT NITRO- GEN-CONTAINING FEEDS TO MIDDLEDISTILLATES The following table indicates results obtainable with thefirst stage catalyst of the present invention and with a low acidityprior art catalyst, and a high acidity prior art catalyst, respectively,when used to hydrocrack a 650 to 1000 F. hydrocarbon feed at theindicated temperatures, and at 1.0 LHSV, 2000 p.s.i.g. and a hydrogenrate of 6500 s.c.f. per barrel, with extinction recycle of unconvertedproducts. The indicated low nitrogen feeds refer to feeds containingfrom zero to p.p.m. nitrogen and the indicated high nitrogen feeds referto feeds containing above 10 p.p.m. nitrogen, for example 10 to 1000ppm. nitrogen.

NiW on S102- 6% Ni+22% 6% Ni on MgO, 27% B10 011 A1203 Slot-A1203, MgO90% Bio:

Temperature, in F. for

50% conversion with low feeds 650 850 550 Temperature, in F. for

50% conversion with high N feeds 740 850 760 Maximum yield of 320650 F.middle distillate, with high N feeds, percent 75-85 75-85 55-65 iCilnCiproduct ratio High Low High Pour point of synthetic middle distillateproduct,

F -40 -00 Relative denitrification aetivit 1.8 1. 0 0. 1 Sensitivity toS"--- Nil Nil Nil Sensitivity to N Low Nil High From the foregoing itwill be seen that the process of the present invention is effective toconvert a wide range of hydrocarbon feeds to valuable products, mainlymiddle distillates, heavy gasoline and light gasoline.

Although only specific embodiments of the present invention have beendescribed, numerous variations could be made in those embodimentswithout departing from the spirit of the invention, and all suchvariations that fall within the scope of the appended claims areintended to be embraced thereby.

We claim:

1. In a process for producing gasoline and middle distillates from ahydrocarbon feed selected from the group consisting of petroleumdistillates boiling from 650 to i2 1100 F. and petroleum residua boilingabove 650 F., which comprises contacting said feed and from 1000 to10,000 s.c.f. of hydrogen per barrel of said feed in a first catalyticconversion zone at a temperature from 500 to 950 F., a pressure from1000 to 2500 p.s.i.g. and an LHSV of 0.1 to 4.0, and producing materialsboiling above 650 F. in a second catalytic conversion zone in thepresence of an acidic catalyst from a 650 F.+ portion of the efiluentfrom said first conversion zone, the improvement which comprises usingin said first conversion zone a catalyst comprising at least onehydrogenating component selected from the Group VI metals and compoundsof Group VI metals and at least one hydrogenating component selectedfrom the Group VIII metals and compounds of Group VIII metals and acatalyst support comprising silica-magnesia, recovering from theeffluent from said first conversion zone a fraction boiling above about650 F., a middle distillate product, a heavy gasoline product and alight gasoline product, withdrawing said products from the system,hydrocracking in a second conversion zone in the presence of an activeacidic hydrocracking catalyst at least a portion of said fraction fromsaid first conversion zone boiling above about 650 F., recovering fromsaid second conversion zone a fraction boiling above about 650 F., amiddle distillate product, a heavy gasoline product and a light gasolineproduct, and returning to said first conversion zone at least a portionof said fraction from said second conversion zone boiling above about650 F., whereby a wide range of products including light and heavygasolines and middle distillates are produced in and recovered from eachof said two conversion zones.

2. A process as in claim 1, wherein said hydrogenating componentselected from the Group VI metals and compounds of Group VI metals ispresent in an amount from 1 to 40 weight percent, based on the totalcatalyst composite.

3. A process as in claim 1, wherein said hydrogenating componentselected from the Group VIII metals and compounds of Group VIII metalsis present in an amount from 1 to 20 weight percent, based on the totalcatalyst composite.

4. A process as in claim 1 wherein said hydrogenating componentscomprise nickel and tungsten.

5. A process as in claim 1 wherein at least two reactors are used insaid first conversion zone, each containing said silica-magnesiasupported catalyst, and wherein said reactors are so arranged that theycan be switched from parallel, for maximizing middle distillateproduction, to series, for maximizing gasoline production, whereby theratio of middle distillate product to gasoline product can be varied.

Eeferences Cited by the Examiner UNITED STATES PATENTS 2,952,611 9/60Haxton et a1. 208 3,047,690 7/62. Myers 20859 3,072,560 1/63 Paterson etal 208111 3,119,765 1/64 Corneil et al. 20859 ALPHONSO D. SULLIVAN,Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,180,817 April 27, 1965 William H. Claussen et al. A

It is hereby certified that error appears in the above numbered patentreqiiring correction and that the said Letters Patent should read ascorrectedbelow.

Column 1, line 16, for "residual" read residua column 5, line 4, for"GROUP" read ZONE line 53, for "20%" read 28% column 9, lines 50 to 52,strike out "with Catalyst A having the lowest acidity increases, theproduct iso to normal ratio in-lyst C is an example" and insert insteadwith Catalyst A having the lowest acidity and Catalyst E having thehighest acidity. Catalyst C is an example Signed and sealed this 28thday of September 1965.

(SEAL) Altest:

ERNEST w. SWIDER EDWARD J. BRENNER Attcsting Officer Commissioner ofPatents

1. IN A PROCESS FOR PRODUCING GASOLINE AND MIDDLE DISTILLATES FROM AHYDROCARBON FEED SELECTED FROM THE GROUP CONSISTING OF PETROLEUMDISTILLATES BOILING FROM 650* TO 1100*F. AND PETROLEUM RESIDUA BOILINGABOVE 650*F., WHICH COMPRISES CONTACTING SAID FEED AND FROM 1000 TO10,000 S.C.F. OF HYDROGEN PER BARREL OF SAID FEED IN A FIRST CATALYTICCONVERSION ZONE AT A TEMPERATURE FROM 500* TO 950*F., A PRESSURE FROM1000 TO 2500 P.S.I.G. AND AN LHSV OF 0.1 TO 4.0, AND PRODUCING MATERIALSBOILING ABOVE 650*F. IN A SECOND CATALYTIC CONVERSION ZONE IN THEPRESENCE OF AN ACIDIC CATALYST FROM A 650*F.+ PORTION OF THE EFFLUENTFROM SAID FIRST CONVERSION ZONE, THE IMPROVEMENT WHICH COMPRISES USINGIN SAID FIRST CONVERSION ZONE A CATALYST COMPRISING AT LEAST ONEHYDROGENATING COMPONENT SELECTED FROM THE GROUP VI METALS AND COMPOUNDSOF GROUP VI METALS AND AT LEAST ONE HYDROGENATING COMPONENT SELECTEDFROM THE GROUP VIII METALS AND COMPOUNDS OF GROUP VIII METALS AND ACATALYST SUPPORT COMPRISING SILICA-MAGNESIA, RECOVERING FROM THEEFFLUENT FROM SAID FIRST CONVERSION ZONE A FRACTION BOILING ABOVE ABOUT650*F., A MIDDLE DISTILLATE PRODUCT, A HEAVY GASOLINE PRODUCT AND ALIGHT GASOLINE PRODUCT, WITHDRAWING SAID PRODUCTS FROM THE SYSTEM,HYDROCRACKING IN A SECOND CONVERSION ZONE IN THE PRESENCE OF AN ACTIVEACIDIC HYDROCRACKING CATALYST AT LEAST A PORTION OF SAID FRACTION FROMSAID FIRST CONVERSION ZONE BOILING ABOVE ABOUT 650*F., RECOVERING FROMSAID SECOND CONVERSION ZONE A FRACTION BOILING ABOVE ABOUT 650*F., AMIDDLE DISTILLATE PRODUCT, A HEAVY GASOLINE PRODUCT AND A LIGHT GASOLINEPRODUCT, AND RETURNING TO SAID FIRST CONVERSION ZONE AT LEAST A PORTIONOF SAID FRACTION FROM SAID SECOND CONVERSION ZONE BOILING ABOVE ABOUT650*F., WHEREBY A WIDE RANGE OF PRODUCTS INCLUDING LIGHT AND HEAVYGASOLINES AND MIDDLE DISTILLATES ARE PRODUCED IN AND RECOVERED FROM EACHOF SAID TWO CONVERSION ZONES.